The task of giving rogues three unique specs is incredibly difficult. Our class design doesn't allow for much flexibility in our mechanics. Assassination, combat, and subtlety all rely on the same energy bar and the same combo points to get the job done. The cyclical rotation of generators and finishers is always going to make up the core of our button presses.
Rogue spec diversity is maintained by three main tenets: differing finishers, interesting cooldowns, and a unique generator mechanic. All rogues will be using Shadow Blades as often as possible and Feint to reduce their damage taken. The utility abilities of the class have been consolidated, and the variance in how we deal our damage is what's left to separate each spec.